"These results continue to underscore the significant potential
benefit of Oncophage in a well-defined, clinically and biologically
relevant subset of patients who are the most appropriate candidates
for cancer vaccines," said Dr. Wood. "In addition, there are
currently no approved therapies for these patients, which represent
a growing and significant population due to increased use of early
detection techniques."

"We are particularly encouraged to see that the clinically
significant trend observed from our earlier analysis has been
strengthened by the updated data from an additional 17-month
follow-up of patients," said Garo H. Armen, PhD, chairman and CEO
of Antigenics. "Although there are challenges associated with
interpretation of subset analyses, the improvement demonstrated in
this group of patients supports the opinion of key experts that
patients with better prognostic factors are the most appropriate
population to benefit from therapeutic cancer vaccines. Combined
with decades of preclinical and clinical cancer vaccine data, we
believe our results provide a higher level of reliability than that
generally associated with outcomes from typical subset
analyses."

Study Findings

Results from the investigator-reported data, which represented
all data collected through the end of study (March 31, 2007),
showed that:

-- Patients receiving Oncophage in the intermediate-risk
population (stages I/II high-grade, III T1/2/3a low-grade) who were
without disease at baseline (n = 362) demonstrated a clinically
significant improvement in recurrence-free survival of
approximately 45 percent (P less than 0.01; HR = 0.55). This
patient population is defined by the Eastern Cooperative Oncology
Group (ECOG) as at intermediate risk for disease recurrence*.
Although the median survival has not yet been reached, results from
the 25th percentile indicate that recurrence-free survival was
extended by approximately 1.8 years in the Oncophage arm.

-- Analysis of overall survival showed improvement associated
with Oncophage in the intermediate-risk population. As of data
cut-off on January 2, 2006, one additional patient had died in the
Oncophage arm versus 13 patients in the observation arm. This now
brings the total reported deaths to 15 patients (8.2 percent) in
the Oncophage arm compared with 25 deaths (14.0 percent) in the
observation arm. The overall survival data are still immature due
to the small number of deaths that have occurred to date; patients
will continue to be monitored for survival through a global patient
registry.

-- Among all eligible patients (intermediate- and high-risk
patients without baseline disease; n = 604), Oncophage was
associated with an 11.4 percent improvement in recurrence-free
survival, which was not statistically significant (HR = 0.89).

-- There was also a promising trend for overall survival
associated with Oncophage in the eligible patient population (n =
604). As of data cut-off on January 2, 2006, 24 additional deaths
have been reported, with six in the Oncophage arm and 18 in the
observation arm, bringing the total to 37 (12.3 percent) and 40
(13.2 percent) deaths, respectively.

-- Adverse events reported during the trial were generally mild
and expected. The more frequently reported adverse events were
mainly constitutional in nature or related to the actual
injection.

The company is working with study investigators to publish the
final findings in a peer-reviewed medical journal.

Antigenics To Continue To Follow Patients for Recurrence-Free
Survival and Overall Survival Through a Global Patient Registry

A global patient registry is being launched to continue
collecting data on all patients from the trial for recurrence-free
survival and overall survival. The registry, which is expected to
provide additional data on the effectiveness of Oncophage, will
follow patients for an additional three years from closure of the
initial trial, providing more than five years' worth of data
collection from the last patient enrolled.

Global Registrational Strategy

Antigenics intends to seek a meeting with US Food and Drug
Administration to discuss the results of the updated analyses
utilizing data through March 2007 to determine whether there is an
opportunity to file a biologics license application (BLA) on the
basis of these results along with appropriate commitments to
conduct further clinical investigations to support the efficacy of
Oncophage in renal cell carcinoma. Antigenics also plans to explore
the need for further clinical studies to support approval of
Oncophage in ex-US markets.

Conference Call Information

Antigenics executives and Dr. Christopher Wood will host a
conference call at 1:30 pm ET today. To access the live call, dial
888.271.9082 (domestic) or 706.679.7741 (international); the access
code is 9197359. The call will also be webcast and will be
accessible from the company's website at
www.antigenics.com/webcast/. A replay will be available
approximately two hours after the call through midnight ET on June
4, 2007. The replay number is 800.642.1687 (domestic) or
706.645.9291 (international), and the access code is 9197359. The
replay will also be available on the company's website
approximately two hours after the live call.

About Renal Cell Carcinoma

Renal cell carcinoma is the most common type of kidney cancer.
The American Cancer Society estimates that there will be
approximately 51,190 new cases of kidney cancer in the United
States in 2007, and about 12,890 people will die from the disease.
Renal cell carcinoma accounts for about 90 percent of all kidney
tumors. By the time renal cell carcinoma is diagnosed in these
patients, about one third of them will have developed metastatic
disease.

The current standard of care for patients with nonmetastatic
renal cell carcinoma consists of a nephrectomy (surgical removal of
the kidney) followed by observation. There is no treatment approved
by the US Food and Drug Administration for nonmetastatic renal cell
carcinoma at the present time.

Antigenics (NASDAQ: AGEN) is a biotechnology company working to
develop treatments for cancers and infectious diseases. The
company's investigational product portfolio includes Oncophage(R)
(vitespen), a patient-specific therapeutic cancer vaccine being
evaluated in several indications; Aroplatin(TM) (L-NDDP), a
liposomal, third-generation platinum chemotherapeutic; AG-707, a
therapeutic vaccine for the treatment of genital herpes; and QS-21,
an adjuvant being evaluated by Antigenics' corporate partners in
more than twenty indications, several in late-stage clinical
trials. For more information, please visit antigenics.com.

This press release contains forward-looking statements,
including statements regarding the potential clinical benefit of
Oncophage in kidney cancer based on a subgroup analysis; the
planned future data to be collected and analyzed in connection with
the future development of Oncophage; and potential strategies for
pursuing the registration of Oncophage. These forward-looking
statements are subject to risks and uncertainties that could cause
actual results to differ materially. These risks and uncertainties
include, among others, unfavorable data resulting from further
analysis of the Oncophage Phase 3 Part 1 trial data; retention of
key employees; the risk that survival data from patients that
withdrew from the study or were lost to follow-up may not be
available for collection or review, or that future survival data
from patient monitoring may not support further development or
registration of Oncophage; decisions by regulatory agencies; the
ability to raise capital and finance future development of
Oncophage; and the factors described under Factors That May Impact
Future Results in the Management's Discussion and Analysis of
Financial Condition and Results of Operations section of
Antigenics' Form 10-Q as filed with the Securities and Exchange
Commission on May 10, 2007. Antigenics cautions investors not to
place considerable reliance on the forward-looking statements
contained in this press release. These statements speak only as of
the date of this document, and Antigenics undertakes no obligation
to update or revise the statements. All forward-looking statements
are expressly qualified in their entirety by this cautionary
statement. Antigenics' business is subject to substantial risks and
uncertainties, including those identified above. When evaluating
Antigenics' business and securities, investors should give careful
consideration to these risks and uncertainties.